Actuators for use in fluid operated braking systems are well known in the art. Such braking systems typically include a service brake air chamber which is connected by way of a mounting tube to the plunger housing of a wedge foundation brake. The air chamber is divided by way of a diaphragm into a pressurized section and a nonpressurized section. Application of fluid pressure, generally air, to the pressurized section flexes the diaphragm causing longitudinal movement of a push rod in the mounting tube. The other end of the push rod is connected to mechanisms for applying braking force, for example, to the wedge assembly of a wedge foundation brake.
The nonpressurized section is normally vented to the atmosphere. Unfortunately, the vents provide passageways for the introduction of road dirt, salt, water or other debris which may adversely affect the operation of the working parts. To prevent this from occurring it has been commonplace to use a boot to close off the end of the tube and seal the parts from these adverse conditions.
Various methods have been employed in the past to mount the boot in the service air chamber. One common technique is to use adhesive to glue the end of the boot to the mounting tube. Among the disadvantages of this approach is that it is a fairly labor intensive operation during assembly and that, once assembled, it is difficult to replace under field service conditions. Other approaches include the provision of retainers or the like attached to the bottom of the air chamber housing for holding the boot in place as illustrated in the promotional literature for Rockwell's "Stop Master" II brakes. Still other techniques include the formation of clips in the lower annular bead of the boot which are adapted to engage the mounting tube. However, none of these approaches have been entirely satisfactory.